1. Technical Field
The invention relates to a semiconductor device, and relates to, for example, a technique applicable to a semiconductor device having a DC/DC converter circuit.
2. Related Art
Techniques regarding a DC/DC converter circuit have been variously examined, and include, for example, techniques disclosed in Japanese Unexamined Patent Publication No. 2011-160651, Japanese Unexamined Patent Publication No. 2006-223016, and PCT Japanese Translation Patent Publication No. 2006-521081.
The technique disclosed in Japanese Unexamined Patent Publication No. 2011-160651 relates to a buck converter circuit in which a control switch and a synchronous switch have a depletion-mode group III nitride switch. In addition, Japanese Unexamined Patent Publication No. 2011-160651 discloses the formation of a protection circuit which is configured so that a current does not flow through the control switch while a control circuit is not powered up.
Japanese Unexamined Patent Publication No. 2006-223016 discloses a non-isolated DC/DC converter in which a high-side switch is a gallium nitride element. PCT Japanese Translation Patent Publication No. 2006-521081 discloses a DC/DC converter including a non-silicon based switching transistor.
In addition, the technique disclosed in PCT Japanese Translation Patent Publication No. 2005-525777 relates to a technique in which a switching element incorporated in a low-side arm of an inverter is a normally-on switching element which allows electrical conduction when a control voltage is not applied.
In order to improve power source efficiency of a DC/DC converter circuit, a reduction in the loss of a switching device constituting the DC/DC converter circuit is required. In order to achieve the reduction in the loss of the switching device, for example, a transistor provided in a compound semiconductor substrate having a two-dimensional electron gas layer may be adopted as the switching device.
On the other hand, when a through-current flows into a circuit in a state where power is not completely supplied to the DC/DC converter circuit, there may be a concern of a transistor or the like constituting a circuit being damaged. However, as disclosed in, for example, Japanese Unexamined Patent Publication No. 2011-160651, when a protection circuit for suppressing such a through-current is newly formed, there may be a concern of a circuit being complicated.
Other problems and novel features will be made clearer from the description and the accompanying drawings of the present specification.